The present disclosure relates to a magnet structure, a clamping mechanism, and an optical disc apparatus.
When a magnet structure is magnetically attached to a magnetically-attached object with a non-magnetic body interposed therebetween, the non-magnetic body is fixed to the magnetically-attached object. For example, in an optical disc apparatus, when a clamper (which is a magnet structure) is magnetically attached to a turntable (which is a magnetically-attached object) with an optical disc (which is a non-magnetic body) interposed therebetween, the optical disc is fixed to the turntable.
By increasing the magnetic attachment force of the magnet structure, the non-magnetic body can be fixed to the magnetically-attached object more reliably. For example, in an optical disc apparatus, recording and reproduction for optical discs require high-speed transfer of information. This needs high speed rotation of optical discs. In order to rotate an optical disc at a high speed, it is important to increase the force holding an optical disc. The force holding an optical disc can be increased by increasing the magnetic attachment force of the clamp.
To detach the non-magnetic body the from magnetically-attached object, the magnet structure needs to be separated from the magnetically-attached object with a force greater than the magnetic attachment force of the magnet structure. If the magnetic attachment force of the magnet structure is increased, therefore, greater force is required to separate the magnet structure. Japanese Unexamined Patent Application Publication No. 9-91815 (Patent Literature 1) discloses an optical disc apparatus including an assist circuit that instantaneously produces high torque to separate the clamp from the turntable.